The present invention relates to an air cleaner for an air-cooled engine, and more particularly to an arrangement of an air passage for separating and removing dust from the air moving into the air cleaner.
When a multipurpose engine is used in a dusty environment or one containing lawn clippings or straw chips or the like, the filter element of the engine air cleaner for the combustion air becomes quickly loaded up with dust or other debris. As a result, the engine performance is reduced and it may even fail.
There has been provided a conventional air cleaner adapted to receive air from the engine cooling fan housing, which has relatively less dust. An air cleaner construction of this type is schematically shown in FIG. 1 of the accompanying drawings, and it is also disclosed in Japanese Patent Provisional Pub. 55-32980 claiming priority of U.S. Ser. No. 938,039 filed on Aug. 30, 1978 now U.S. Pat. No. 4,233,043.
In FIG. 1, a fan housing 1 encloses a fan 3 which rotates to produce a cooling wind delivered to the cylinder section and the main parts of the engine. In the side wall of the housing 1 is formed a straight air passage 4, through which passes a portion of the wind into the atmosphere. The passage 4 has an intermediate branch 6 extending perpendicularly thereto and leading to an air cleaner 5, which communicates with a carburetor 2. Dust in the air moving through the passage 4 is moved straight through the passage 4 and is discharged into the atmosphere by its inertia, whereas relatively clean air is sucked into the cleaner 5.
However, since the dust distribution in the air in the cross section of the passage 4 is even, a portion of the dust passing by the suction port 6a may be sucked into the branch 6 if the inertia of the dust particles is low. The inertia could be made larger by increasing the amount of the wind, but this would necessitate an enlargement of the size of the fan.